A phase I/II, open-label, randomised study of nintedanib plus mFOLFOX6 versus bevacizumab plus mFOLFOX6 in first-line metastatic colorectal cancer patients

BACKGROUND

This randomised, open-label, phase I/II study evaluated the efficacy and safety of nintedanib, an oral, triple angiokinase inhibitor, combined with chemotherapy, relative to bevacizumab plus chemotherapy as first-line therapy in patients with metastatic colorectal cancer (mCRC).

PATIENTS AND METHODS

Patients with histologically confirmed mCRC (adenocarcinoma), an Eastern Cooperative Oncology Group performance status ≤ 2 and adequate organ function were included. Patients were randomised 2:1 to receive nintedanib 150 mg or 200 mg b.i.d. plus mFOLFOX6 (oxaliplatin 85 mg/m(2), l-leucovorin 200 mg/m(2) or d,l-leucovorin 400 mg/m(2), 5-fluoruracil bolus 400 mg/m(2) followed by 2400 mg/m(2), every 2 weeks) or bevacizumab (5 mg/kg every 2 weeks) plus mFOLFOX6. During phase I, patients underwent a 3 + 3 dose-escalation schema to determine the maximum tolerated dose (MTD) of nintedanib in combination with mFOLFOX6. The primary end point was progression-free survival (PFS) rate at 9 months. Objective response (OR) was a secondary end point.

RESULTS

The nintedanib recommended phase II dose was 200 mg b.i.d. plus mFOLFOX6 based on safety data from phase I (n = 12). Of 128 patients randomised in the phase II part, 126 received treatment (nintedanib plus mFOLFOX6, n = 85; bevacizumab plus mFOLFOX6, n = 41). PFS at 9 months was 62.1% with nintedanib and 70.2% with bevacizumab [difference: -8.1% (95% confidence interval -27.8 to 11.5)]. Confirmed ORs were recorded in 63.5% and 56.1% of patients in the nintedanib and bevacizumab groups, respectively. The incidence of adverse events (AEs) considered related to treatment was 98.8% with nintedanib and 97.6% with bevacizumab; the incidence of serious AEs was 37.6% with nintedanib and 53.7% with bevacizumab. The pharmacokinetics of nintedanib and the components of mFOLFOX6 were unaffected by their combination.

CONCLUSIONS

Nintedanib in combination with mFOLFOX6 showed efficacy as first-line therapy in patients with mCRC with a manageable safety profile and further studies in this population are warranted.

Abstract 3568: CYP3A4 epoxygenase activity mediates ER+ mammary tumor growth and angiogenesis, in part, through EET biosynthesis and is inhibited by biguanides

While cytochrome P450 enzymes (CYPs) are implicated in tumor angiogenesis through biosynthesis of epoxyeicosatrienoic acids (EETs), little is known about breast cancer cell-intrinsic CYPs that exhibit epoxygenase activity, such as CYP3A4. In an orthotopic breast cancer model, silencing of epithelial CYP3A4 suppressed angiogenesis-related escape of ER+ breast tumors from dormancy. While the diabetes drug metformin inhibits mitochondrial complex I and inhibits tumor growth, how it does so is unknown. Metformin inhibited CYP epoxygenase activity and co-crystallized in the active site of CYP3A4, hydrogen bonding with arginine 212, allowing the development of hexyl-benzyl-biguanide (HBB) as a CYP3A4 inhibitor using molecular modeling. HBB exhibited more than 10-fold greater potency than metformin for inhibition of ER+ mammary tumor growth and inhibited associated tumor angiogenesis. HBB inhibited EET biosynthesis ∼40-fold more potently than metformin and was ∼40-fold more potent for activation of AMPK phosphorylation. EETs suppressed and CYP silencing promoted AMPK phosphorylation, linking CYPs with AMPK regulation in breast cancer. HBB depolarized mitochondria, reduced oxygen consumption rates and suppressed the Warburg effect, while EETs restored the mitochondrial membrane potential. CYP3A4 silencing and HBB treatment increased reactive oxygen species (ROS) production, suggesting that CYPs suppress cancer cell death, in part, through suppression of ROS. CYP3A4 silencing sensitized breast cancer cells to hormonal therapy and chemotherapy, abrogated by EETs. Because EETs are autocrine, paracrine and endocrine, these results implicate CYPs in tumor growth, in part, through cell-cell mediation of mitochondrial homeostasis and demonstrate the potential of CYP3A4 as a therapeutic target in breast cancer.

Citation Format: Zhijun Guo, Irina F. Sevrioukova, Eric Hanse, Ilia Denisov, Xia Zhang, Ting-Lan Chiu, Daniel Swedien, Justin Stamschror, Juan Alvarez, William Marerro Ortiz, Monique Morgan, Michael Maher, Kathryn J. Chavez, Dafydd Thomas, Young Kyung Bae, Jonathan Henriksen, Beverly Norris, Robert J. Schumacher, Henry Wang, Robin Bliss, Haitao Chu, Rebecca Cuellar, Thomas L. Poulos, Stephen G. Sligar, William Atkins, Stephen Schmechel, Jorge Capdevila, John Falck, Ian Blair, Jeffrey P. Jones, Gunda Georg, Kalpna Gupta, Ameeta Kelekar, Elizabeth Amin, David A. Potter. CYP3A4 epoxygenase activity mediates ER+ mammary tumor growth and angiogenesis, in part, through EET biosynthesis and is inhibited by biguanides. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3568. doi:10.1158/1538-7445.AM2015-3568

Pazopanib in pretreated advanced neuroendocrine tumors: a phase II, open-label trial of the Spanish Task Force Group for Neuroendocrine Tumors (GETNE)

BACKGROUND

The management of advanced neuroendocrine tumors (NETs) has recently changed. We assessed the activity of pazopanib after failure of other systemic treatments in advanced NETs.

METHODS

This was a multicenter, open-label, phase II study evaluating pazopanib as a single agent in advanced NETs (PAZONET study). The clinical benefit rate (CBR) at 6 months was the primary end point. Translational correlation of radiological response and progression-free survival (PFS) with circulating and tissue biomarkers was also evaluated.

RESULTS

A total of 44 patients were enrolled. Twenty-five patients (59.5%) were progression-free at 6 months (4 partial responses, 21 stable diseases) with a median PFS of 9.5 months [95% confidence interval (CI) 4.8-14.1]. The CBR varied according to prior therapy received, with 73%, 60% and 25% in patients treated with prior multitarget inhibitors, prior mTOR inhibitors and both agents, respectively. A nonsignificant increase in PFS was observed in patients presenting lower baseline circulating tumor cell (CTC) counts (9.1 versus 5.8 months; P = 0.22) and in those with decreased levels of soluble-vascular endothelial growth factor receptor-2 (sVEGFR-2) (12.6 versus 9.1 months; P = 0.067). A trend toward reduced survival was documented in patients with VEGFR3 rs307821 and rs307826 missense polymorphisms [hazard ratio (HR): 12.3; 95% CI 1.09-139.2; P = 0.042 and HR: 6.9; 95% CI 0.96-49.9; P = 0.055, respectively].

CONCLUSIONS

Pazopanib showed clinical activity in patients with advanced NETs regardless of previous treatments. Additionally, CTCs, soluble-s VEFGR-2 and VEGFR3 gene polymorphisms constitute potential biomarkers for selecting patients for pazopanib (NCT01280201).

CLINICAL TRIAL NUMBER

NCT01280201.

GEP-NETs update: Biotherapy for neuroendocrine tumours

Neuroendocrine tumours (NETs) represent a less frequent and heterogeneous group of tumours, which has experienced, in recent years, a significant increase in effective therapeutic possibilities overcoming the disappointing results from chemotherapy. Initial improvements in treatment strategies came from somatostatin analogues (SSAs) that have widely demonstrated a significant improvement in symptomatic relief and tumour control growth by a complex mechanism of action over cell survival, angiogenesis and immunomodulation. Recent investigations have pointed out novel SSAs with a wider binding profile (pasireotide), chimeric molecules against somatostatin receptors and dopamine receptors and the combination with targeted agents, such as mTOR inhibitors or antiangiogenic agents. Immunotherapy is the second cornerstone in NET treatment and has been represented with interferon alpha for a long time, with a demonstrated activity on tumour and clinical response. Its less manageable adverse events have limited its usage. However, different checkpoints in immune system regulation have been effectively targeted in different solid tumours, and novel approaches are currently arising in NETs. In conclusion, biotherapy remains an active treatment strategy for initial approach in patients with NETs. Further investigation on patients' selection, molecular profiles, treatment sequence or combination and optimisation of current and novel biotherapy agents is required.

Abstract 2689: Breast cancer inhibition by a novel and potent biguanide, N1-hexyl-N5-benzyl-biguanide

Metformin is a widely used biguanide diabetes drug that is associated with decreased breast cancer risk and is currently being studied for treatment and prevention of breast cancer. While metformin and biguanides buformin and phenformin exhibit inhibitory activity against breast cancer in vitro and in vivo, they lack potency (IC50=5-20 mM) and their mechanisms of action remain unclear. More potent biguanides may provide insights into biguanide anti-cancer activity and we therefore studied the novel biguanide N1-hexyl-N5-benzyl-biguanide mesylate (HBB), which potently inhibits the MCF-7 and MDA-MB-231 breast cancer lines (IC50=20 uM for both lines). HBB induces AMPK phosphorylation in both lines at 10 uM concentration, whereas similarly dosed metformin, buformin or phenformin exhibits no activity. HBB also inhibits STAT3 phosphorylation at 10 uM concentration, whereas metformin dosed at 10 uM exhibits no activity. HBB reduced the mitochondrial membrane potential of both lines, but the effect was more prominent in the MDA-MB-231 line. HBB also induced ROS within 2.5 hours of exposure in the MCF-7 and MDA-MB-231 lines and caused rapid necrosis, but not apoptosis. N-acetylcysteine provides partial protection from HBB for MDA-231 line, but not the MCF-7 line. HBB provides proof of principle that highly potent biguanides can be synthesized with at least 250-fold greater potency than metformin, which can provide insights into the cancer inhibitory mechanisms of biguanide drugs. R01 CA113570, Randy Shaver Foundation, CTSI University of Minnesota

Citation Format: Zhijun Guo, Kathryn J. Chavez, Juan Alvarez, Xia Zhang, Beverly Norris, Michael Maher, Monique Morgan, Robert J. Schumacher, Rebecca Cuellar, Irina F. Sevrioukova, Thomas L. Poulos, Ilia Denisov, Stephen G. Sligar, Kalpna Gupta, Ian A. Blair, Jorge Capdevila, Ameeta Kelekar, Elizabeth Amin, Gunda Georg, David A. Potter. Breast cancer inhibition by a novel and potent biguanide, N1-hexyl-N5-benzyl-biguanide. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2689. doi:10.1158/1538-7445.AM2014-2689

Abstract 342: Vascular Endothelial Ace Deletion Or AT1R Blockade Reduces Blood Pressure But Does Not Prevent Vascular Remodeling In Models Of 20-HETE-Dependent Hypertension

20-HETE-mediated hypertension in rats and mice is associated with increased vascular ACE expression and Ang II levels. We examined the contribution of vascular ACE to blood pressure (BP) and vascular remodeling in 20-HETE-dependent hypertension. The ACE3/3 mice lack vascular endothelial ACE, exhibit attenuated renal ACE expression and display normal plasma ACE and Ang II levels. Administration of 5α-dihydrotestosterone (DHT) (100 mg; 21-day pellet), an inducer of 20-HETE production, increased systolic BP (SBP) by 50% in WT mice (148±4 vs 99±2 mmHg) and 26% in ACE 3/3 mice (125±1 vs 99±1 mmHg). Administration of losartan (10 mg/kg/day) or 20-HEDGE (20-HETE antagonist, 10mg/kg/day) at day 14 of DHT treatment reduced SBP in WT and ACE3/3 mice to levels of untreated mice. DHT increased ACE protein in WT by 2.3-fold in mesenteric and 2.6-fold in aortic arteries while ACE3/3 mice lacked vascular ACE expression which remained absent under DHT treatment. DHT increased preglomerular microvessel (PGMV) remodeling in WT and ACE3/3 mice; however, remodeling was attenuated in ACE3/3 mice (media thickness, 14.54±1.24 vs 9.80±0.56 μm; p<0.05) as opposed to WT mice (22.17±0.92 vs 9.68±0.76 μm; p<0.05). In Cyp4a12tg mice, in which the expression of the Cyp4a12-20-HETE synthase is under the control of the doxycycline (DOX) promoter, DOX (1 mg/ml drinking water) increased SBP (136±2 vs 102±1 mmHg; p<0.05). The increase in SBP was prevented by co-treatment with 20-HEDGE (103±3mmHg), lisinopril (100±3mmHg), or losartan (102±3mmHg). DOX treatment increased PGMV remodeling when compared to untreated Cyp4a12tg mice (media thickness, 16.1±0.9 vs. 8.2±0.5 μm, p<0.05). Co-treatment with 20-HEDGE (10 mg/kg/day) prevented DOX-induced PGMV remodeling (8.8±0.6 μm, p<0.05) while co-treatment with lisinopril or losartan attenuated but did not prevent PGMV remodeling (12.0±0.5 and 11.1±0.5 μm). DOX-treated Cyp4a12tg displayed increased ACE expression in PGMV which was negated by treatment with 20-HEDGE but unaffected by either losartan or lisinopril treatment. These results suggest that vascular endothelial ACE contributes, in part, to 20-HETE-mediated microvascular remodeling in hypertension and that 20-HETE have effects on microvascular remodeling independent of RAS.

Abstract 047: 20-SOLA, A Novel Water-soluble 20-HETE Antagonist, Elicits Natriuresis And Abrogates Hypertension In Cyp4a14 Knockout Mice

20-HETE (20-hydroxyeicosatetraenoic acid) is a cytochrome P450 (CYP) 4A-derived arachidonate metabolite. In the vasculature, 20-HETE increases smooth muscle contraction, endothelial dysfunction/activation and sensitivity to constrictor stimuli; all of which contribute to hypertension. In renal tubules, 20-HETE inhibits ion transport and has pro-natriuretic functions in salt-sensitive models of hypertension. The pro-natriuretic effect of 20-HETE has not been reported in mouse models of 20-HETE-dependent hypertension. The CYP4a14 knockout (KO) male mice exhibit androgen-dependent upregulation of Cyp4a12, the sole 20-HETE synthase in mice, and display 20-HETE-dependent hypertension; female KO mice show no increase in Cyp412-20-HETE and are normotensive. We examined the effect of 20-SOLA (2,5,8,11,14,17-hexaoxanonadecan-19-yl-20-hydroxyeicosa-6(Z),15(Z)-dienoate), a water-soluble 20-HETE antagonist, and determined its effect on blood pressure (BP) and natriuresis in the KO mice. Administration of 20-SOLA (10mg/kg/day in drinking water) normalized BP in male KO mice; a significant reduction was observed on day 4 (146±1 vs153±2 mmHg in untreated littermates) reaching BP of the normotensive female KO mice (124±1 and 126±1 mmHg for treated and untreated, respectively) at day 10 of treatment (124±1 vs. 153±2 mmHg in untreated male KO; p<0.05). 20-SOLA decreased vascular reactivity to phenylephrine in male KO renal microvessels by 7-fold (EC50: 1.58±0.23 vs 0.22±0.03 μM). Moreover, treatment with 20-SOLA increased urine output in KO male mice as compared to untreated littermates (1.25±0.04 vs. 1.06±0.04 mL; p<0.05). The urine output to water intake ratio was significantly elevated in 20-SOLA-treated KO vs. untreated (0.25±0.01 vs. 0.19±0.01, p<0.05). Importantly, treatment with 20-SOLA increased urinary sodium excretion in the KO male mice (12.33±0.44 vs. 8.33±0.63 μmol/gr BW/24Hrs; p<0.05). These results suggest that 20-HETE has an anti-natriuretic effect in the kidneys of KO mice and that antagonism of 20-HETE’s action using 20-SOLA elicited natriuresis concurrent with reduction in blood pressure. The potential vascular and tubular mechanisms underlying 20-HETE anti-natriuretic action are being currently explored.

Abstract 534: Cytochrome P450 epoxygenase regulates Na transport in aldosterone-sensitive distal nephron: a lesson learns from Cyp2c44 knockout mice

Previous study demonstrated that the down-regulation of epoxygenase caused salt-sensitive hypertension. We used the real-time PCR technique to demonstrate that a high Na (4% Na) intake increased the Cyp2c44 expression in the thick ascending limb and distal convoluted tubule (DCT) and connecting tubule (CNT). The disruption of cyp2c44 increased ENaC activity in CNT and the 40 pS inwardly-rectifying K channel, a heterotetramer of Kir.4.1/Kir5.1, in the basolateral membrane of early segment of DCT (DCT1). Application of epoxyeicosatrienoic acid (EET) inhibited both ENaC in the CNT and the Kir4.1/5.1 channels in DCT1. Kir4.1/5.1 plays a key role in generating the cell membrane potential in the DCT and is the only type of K channels responsible for providing K conductance in the basolateral membrane of the DCT. Also, we demonstrated that Kir.4.1/5.1 activity determines the apical NCC expression and Ste20-related-proline-alanine-rich kinase (SPAK) which stimulates NCC activity through the phosphorylation of NCC. Since EET inhibited Kir4/1/5.1 in the DCT, the disruption of Cyp2c44 significantly increased the basolateral Kir4.1/5.1 activity thereby increasing the expression of SPAK and NCC in cyp2c44 knockout mice. Thus, feeding Kcnj10 knockout mice with high Na caused hypertension. Moreover, the application of amiloride failed to completely reverse the Na-sensitive hypertension in the knockout mice while the application of thiazide and amiloride restored the normal blood pressure in Kcnj10 knockout mice. We conclude that Cyp2c44 plays an important role in suppressing NCC in the DCT and ENaC in the CNT during increasing dietary Na intake. The upregulation of NCC expression in Kcnj10 -/- mice was due to the stimulation of the basolateral K channels in the DCT.

Abstract 355: Mineralocorticoid Receptor Activation Alters Epoxyeicosatrienoic Acid Production In Vivo

Epoxyeicosatrienoic acids (EETs) are products of CYP450 epoxygenase and are degraded to DHETs by soluble epoxide hydrolase (sEH). Their natriuretic and vasodilatory actions oppose those of mineralocorticoids, but the effect of aldosterone on EET metabolism has not been investigated. To test the hypothesis that aldosterone impairs EET metabolism via altered production or degradation, we treated wild type C57Bl6J mice with aldosterone (50 μg/kg/d) or vehicle ± the mineralocorticoid receptor (MR) antagonist RU-28318 during high sodium intake for 2 weeks. Aldosterone decreased plasma ( Fig A ; -29%, 4.4±0.6 vs. 3.1±0.4 ng/ml, control vs. aldosterone) and pancreatic EETs ( Fig B ;-43%, 112±15 vs. 64±15 ng/mg tissue, control vs. aldosterone) but not hepatic or kidney EETs. MR antagonism prevented this effect of aldosterone on plasma EETs. The urinary DHET/EET ratio markedly increased, suggesting increased renal sEH activity. Because both aldosterone and EETs affect insulin secretion, we further assessed CYP epoxygenase expression within the pancreas. We detected Cyp2c44 and sEH ( Ephx2) mRNA in isolated murine islets, and immunohistochemistry demonstrated CYP2C expression in beta-cells. Aldosterone decreased protein expression of CYP2C epoxygenase within whole pancreas, and ex vivo aldosterone treatment decreased Cyp2c and increased sEH mRNA expression within isolated islets. These data demonstrate that aldosterone decreases CYP2C expression and EET production in vivo . We propose that the renin-angiotensin-aldosterone system interacts with the CYP450 epoxygenase system to alter blood pressure and glucose homeostasis via EET metabolism.

Role of cytochrome P450 epoxygenase in regulating renal membrane transport and hypertension

PURPOSE OF REVIEW

Cytochrome P450 (CYP)-epoxygenase is highly expressed in the kidney and its metabolism of arachidonic acid plays important roles in regulating renal Na transport and in modulating vasoactivity in the kidney. In the past several years, progress has been made not only in characterizing the specific CYP-epoxygenases responsible for the regulation of membrane transport and vasoactivity in the kidney but also in exploring the mechanism by which they regulate renal Na transport and vasodilation of preglomerular arterioles. This review summarizes and updates recent progress in this area of research.

RECENT FINDINGS

CYP-epoxygenase metabolites of arachidonic acid inhibit epithelial Na channel (ENaC) in the cortical collecting duct (CCD), and 11,12-epoxyeicosatrienoic acid (11,12-EET) is mainly responsible for mediating the inhibitory effect on ENaC. Downregulation of CYP2C44 abolishes arachidonic acid mediated inhibition of ENaC and increases ENaC activity. In addition, 11,12-EET stimulates Ca-activated big conductance K channels in the CCD and afferent arterioles smooth muscles. Activation of big conductance K channels by 11,12-EET is responsible for EET-induced vasodilation in preglomerular arterioles. 11,12-EET-induced vasodilation is absent in preglomerular arterioles pretreated with okadaic acid.

SUMMARY

CYP-epoxygenase mediated suppression of renal Na transport is partially achieved by inhibition of ENaC activity in the CCD and CYP2C44-derived EETs are responsible for inhibition of ENaC. Stimulation of serine/threonine protein phosphatase 2A (PP2A) contributes to 11,12-EET-induced activation of big conductance K channels and vasodilation in preglomerular arterioles.

Abstract 340: Deletion of Cyp2c44-epoxygenase in the Collecting Duct Causes the Hypertension in Mice on a High K Diet

Previous studies demonstrated that high K (HK) intake caused hypertension in Cyp2c44 (-/-) mice. In the present study we examined the role of Cyp2c44 in the collecting duct (CD) in blood pressure (BP) regulation during increased K intake in a CYP2c44 CD-specific conditional knockout mice (KO). CD specific KO mice were generated by crossing Cyp2c44(flx/flx) mice (a generous gift of from D. Zeldin, MD) with a Hoxb7-Cre+ mice. The KO mice have normal body development and show no visible differences when compared to wt mice. However, increasing dietary K intake from 1% to 4% significantly increased the BP of KO mice (from 125 mmHg to 148 mmHg) but, not that of wt mice. In contrast, feeding KO mice with high salt (4% or 8%) had no significant effect on their BP (126 mmHg). A high (HK) intake also slightly but significantly increased plasma Na concentration of KO mice from 149 mM to 150.3 mM. Moreover, single tubule-real-time PCR experiments demonstrated that a HK intake increased the expression of Cyp2c44 mRNA by 10 folds in the distal convoluted tubule (DCT) but only had a modest effect in the TAL and no effect on Cyp2c44 expression in proximal tubules. Thus, a HK intake is still able to stimulate Cyp2c44 expression in the DCT. Because administration of amiloride decreased the BP of the KO mice on a HK diet to 117 mmHg, we speculate that defective regulation of ENaC by the Cyp2c44 epoxygenase may be responsible for the HK intake-induced hypertension in the KO mice. This speculation was confirmed by patch-clamp experiments performed in the isolated CD of the KO mice. Application of arachidonic acid (AA) inhibited ENaC in the wt mice but failed to inhibit Na channels in the KO mice. However, adding 11,12-EET inhibited ENaC in both wt and KO mice. We conclude that the CD Cyp2C44-epoxygenase in is essential for suppressing ENaC activity in the CD and for preventing hypertension in response to a HK intake.